Lignin derived Si@C composite as a high performance anode material for lithium ion batteries

Carbon coated 50 nm Si NPs using alkali lignin (AL) or alkali lignin-derived azo polymer (AL-azo-NO2) as the low cost carbon precursors were synthesized. The Si@C composites were facilely prepared by evaporating solvent THF of the Si NPs/carbon precursor dispersion solutions followed by carbonization in nitrogen. The resulting Si@C composites showed a vesical-like morphology with integrated carbon coating on Si NPs. When used as the anode materials for Li-ion batteries, the nitrogen-doped carbon coated Si NPs (Si@C-AL-azo-NO2) stemmed from the use of AL-azo-NO2 showed superior electrochemical performance. As the results, Si@C-AL-azo-NO2 exhibited a high reversible specific capacity of 882 mAh/g at a current of 200 mA/g over 150 cycles and a high coulombic efficiency (99%), paving the way for promising application of lignin in high performance Si@C anode materials for Li-ion batteries.